﻿
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using System.Security.Cryptography;
using System.Text;

namespace LowCoding.Common.Security
{
    /// <summary>
	/// RSA加密解密及RSA签名和验证
	/// </summary>
	public class RSACryption
    {
        public RSACryption()
        {
        }

        #region RSA 加密解密

        /// <summary>
        /// RSA加密函数
        /// </summary>
        /// <param name="rawInput"></param>
        /// <param name="publicKey"></param>
        /// <returns></returns>
        public static string RsaEncrypt(string rawInput, string publicKey)
        {
            if (string.IsNullOrEmpty(rawInput))
            {
                return string.Empty;
            }

            if (string.IsNullOrWhiteSpace(publicKey))
            {
                throw new ArgumentException("Invalid Public Key");
            }

            publicKey = RSAPublicKeyJava2DotNet(publicKey);

            using (var rsaProvider = new RSACryptoServiceProvider())
            {
                var inputBytes = Encoding.UTF8.GetBytes(rawInput);//有含义的字符串转化为字节流
                rsaProvider.FromXmlString(publicKey);//载入公钥
                int bufferSize = (rsaProvider.KeySize / 8) - 11;//单块最大长度
                var buffer = new byte[bufferSize];
                using (MemoryStream inputStream = new MemoryStream(inputBytes),
                     outputStream = new MemoryStream())
                {
                    while (true)
                    { //分段加密
                        int readSize = inputStream.Read(buffer, 0, bufferSize);
                        if (readSize <= 0)
                        {
                            break;
                        }

                        var temp = new byte[readSize];
                        Array.Copy(buffer, 0, temp, 0, readSize);
                        var encryptedBytes = rsaProvider.Encrypt(temp, false);
                        outputStream.Write(encryptedBytes, 0, encryptedBytes.Length);
                    }
                    return Convert.ToBase64String(outputStream.ToArray());//转化为字节流方便传输
                }
            }
        }

        #endregion RSA 加密解密

        /// <summary>
        /// RSA公钥格式转换，java->.net
        /// </summary>
        /// <param name="publicKey">java生成的公钥</param>
        /// <returns></returns>
        public static string RSAPublicKeyJava2DotNet(string publicKey)
        {
            RsaKeyParameters publicKeyParam = (RsaKeyParameters)PublicKeyFactory.CreateKey(Convert.FromBase64String(publicKey));
            return string.Format("<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent></RSAKeyValue>",
                Convert.ToBase64String(publicKeyParam.Modulus.ToByteArrayUnsigned()),
                Convert.ToBase64String(publicKeyParam.Exponent.ToByteArrayUnsigned()));
        }
    }
}